Add --os-cloud support

This adds a new option --os-cloud that allows the configuration values
for multiple clouds to be stored in a local file and selected with
a single option.

Internal option names have had 'os_' removed to be comptible with
the options returned from OpenStackConfig().get_one_cloud().

The config file is ~/.config/openstack/clouds.yaml:

Sample
------
clouds:
  devstack:
    auth:
      auth_url: http://192.168.122.10:35357/
      project_name: demo
      username: demo
      password: 0penstack
    region_name: RegionOne
  devstack:
     auth:
       auth_url: http://192.168.122.10:35357/
       project_name: demo
       username: demo
       password: 0penstack
     region_name: RegionOne

Co-Authored-By: Monty Taylor <mordred@inaugust.com>
Change-Id: I4939acf8067e44ffe06a2e26fc28f1adf8985b7d
Depends-On: I45e2550af58aee616ca168d20a557077beeab007

examples/object_api.py

@@ -30,6 +30,8 @@ import common
 from openstackclient.api import object_store_v1 as object_store
 from openstackclient.identity import client as identity_client
 
+from os_client_config import config as cloud_config
+
 
 LOG = logging.getLogger('')
 
@@ -37,6 +39,15 @@ LOG = logging.getLogger('')
 def run(opts):
     """Run the examples"""
 
+    # Look for configuration file
+    # To support token-flow we have no required values
+    # print "options: %s" % self.options
+    cloud = cloud_config.OpenStackConfig().get_one_cloud(
+        cloud=opts.cloud,
+        argparse=opts,
+    )
+    LOG.debug("cloud cfg: %s", cloud.config)
+
     # Set up certificate verification and CA bundle
     # NOTE(dtroyer): This converts from the usual OpenStack way to the single
     #                requests argument and is an app-specific thing because
@@ -52,13 +63,13 @@ def run(opts):
     # The returned session will have a configured auth object
     # based on the selected plugin's available options.
     # So to do...oh, just go to api.auth.py and look at what it does.
-    session = common.make_session(opts, verify=verify)
+    session = common.make_session(cloud, verify=verify)
 
     # Extract an endpoint
     auth_ref = session.auth.get_auth_ref(session)
 
-    if opts.os_url:
-        endpoint = opts.os_url
+    if opts.url:
+        endpoint = opts.url
     else:
         endpoint = auth_ref.service_catalog.url_for(
             service_type='object-store',